Determining the geographical location of a cellular phone is useful in a variety of applications, including applications in the field of location-based services. In traffic information systems, for example, the locations of vehicles may be determined based on the locations of drivers' cellular phones, in order to form an image of traffic conditions. The location of a cellular phone can be determined based on data acquired from the cellular network itself. In particular, the location can be specified in terms of the network cell in which the cellular phone is located, as defined by a cell-identifier, possibly in addition to other data such as a time-advance.
There is an ongoing need, however, for accurate techniques of determining the geographical location of cellular phones, in many applications.